Rheostat



Jan. 21, 1930. w, c, MCCOY 1,744,481.

RHEOSTAT Filed July 31, 1926 3 Sheets-Sheet 1 INVENTOR wl ATTORNEY W. C. M COY Jan. 21, 1930.

RHEOSTAT Filed July 31, 1926 3 Sheets-Sheet 2 I I INVENTOR Wllham QME o Jan. 21, 1930. w, 3, MCCOY 1,744,481

RHEOSTAT Filed July 31, 1926 3 Sheets-Sheet 3 @mw h INVENTOR William CH 1 ATTORNEYS Patented Jan. 21, 1930 UNITED STATES PATENT OFFICE WILLIAM C. MCCOY, F CLEVELAND, OHIO, ASSIGNOR TO THE CLEVELAND TRUST COM- PANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO RI-IEOSTA'I' Application filed July 31,

This invention relates to liquid level operated rheostat mechanisms and it particularly pertains to a type of rheostat for use in connection with remote controlled indicators that is adapted to be inserted in the fuel receiving opening of a fuel tank and to provide a supplemental opening through which fuel can be supplied to the tank.

One of the objects of my invention is to 1;- provide a rheostat of the character specified that can conveniently be mounted in the fluid receiving opening of a tank of conventional form without in any way modifying the tank structure.

Another obj ect of my invention is to provide a new form of rheostat chamber and improved contact mechanism for operation in connect-ion therewith.

An additional object of my invention is to so arrange the rheostat receiving chamber of the unit as to receive and position a rheostat winding of suitable form.

A further object of my invention is to provide an improved contact means adapted to provide an external connection to a swingable contact arm that is adapted to electrically engage the resistance winding of the rheostat.

Figure 1 of the accompanying drawings is a longitudinal sectional view of a rheostat constructed in accordance with my invention mounted within the fuel tank of an automobile and connected to a suitable indicating instrument.

Fig. 2 is a longitudinal sectional view taken substantially on line 22 looking in the direction of the arrows of the rheostat unit shown in Fig. 1 with the connecting cable removed.

Fig. 8, Fig. 4, and Fig. are transverse sectional views of the body portion of the rheostat taken substantially on lines 33, 4 l and 55 of the body portion of the rheostat shown in Fig. 2 and looking toward its lowermost extremity.

Fig. 6 is a top plan view of the rheostat shown in Fig. 1 with the cover removed.

Fig. 7 is an exploded view, shown in perspective, of the rheostat structure.

Fig. 8 is a perspective view of a terminal block of insulating material used in connec- 1926. Serial No. 126,238.

tion with the rheostat chamber and serving as a terminal block.

Fig. 9 is an exploded view of the contact arm shown in its disassembled relation; and

'Fig. 10 is a lateral side view of the lower portion of the rheostat unit with the float arm removed.

The rheostat device shown in Fig. 1 cmbodies a base 1, preferably of die cast nonmagnetic material, that is mounted in the fuel receiving tank 2 of an automobile or other device by a supporting collar 3. The rheostat unit is connected to a suitable indicator that is preferably mounted on the panel of the automobile.

The head portion of the base 1 has an open top rheostat receiving chamber 5 that is positioned to one side of a threaded fuel receiving opening 6. The rheostat receiving chamber 5 has a cylindrical wall portion 13 that terminates at one end adjacent the fuel receiving opening and at the other end adjacent an upstanding flange 7 which serves to define a supplemental compartment for receiving an insulating contact block 8. The cylindrical wall portion 13 of the rheostat chamber extends below the remainder of the bottom of the chamber, thereby providing a groove 9 of partially annular form that is adapted to receive a resistance winding 14 that is held 0 in place within the rheostat cavity by its close fit therewith and by the arcuate form to which it is bent.

The base has a depending hollow body portion that extends into the tank from the head portion and that provides a suitable support for the float mechanism. The body portion is reenforced' by a series of outstanding arcuate webs 11 that greatly increase its strength. A longitudinal cavity 12 extends the length of the body for receiving an operating shaft 15 that extends therethrough'. The lower end of the hollow body portion has a bushing 10 that provides a bearing portion for the operating shaft. A pair of shaft supporting arms 16 and 17 are formed at the extremity of the body for receiving suitable pivot screws 18 and 19 that support a bevel gear 20 therebetween. The bevel gear 20' is connected to a suitable float 21 by the arm 22. The bevel gear 20 meshes with a bevel pinion 26 that is carried by the lower end of the shaft 15. A stop 23 engages opposed shoulders 24 that are formed on the arm 16 and serve to limit the movement of the float arm 22. The upper end portion 33- of the operating shaft 15 is bent at right angles to fit within a cavity 34 that is formed in an insulating arm 30 that is swingable with the portion 33 and is mounted within the rheostat receiving cavity. A bearing face 35 is formed on the underside of the rheostat block in order to reduce the friction of the arm and a flexible-contact finger 31 is secured in a suitably formed cavity molded into the side of the block 30 by rivet 32. The flexible contact finger 31 has a contacting face 36 that is adapted to engage a flexible contact finger 37 that is'carried by the insulating block 8. A suitable screw 25 enters the underside of the head portion of the device to secure the insulating block 8 in position. a

A cover plate 28 serves to close the rheostat chamber and also provides an opening that registers with the fuel receiving opening 6 of the body portion. The body portion 1 of the device is secured to the supporting collar 3 by suitable screws 27 that extend through openings 62 in the base into threaded openings 61 in the supporting collar. A suitable cap 29 is threaded to engage the corresponding threads of the body portion to close the fuel receiving opening of the device.

The resistance winding 14 is preferably formed of enameled resistance wire that is wound helically on a strip 38 of insulating fiber. The inner face of the completed winding is then buffed to remove the insulation. A strip of insulating material, such as paper 39, is folded with its edges overlying the edges of the rheostat unit in order to effectively insulate the resistance unit from the metal chamber. One end 41 of the resistance winding is grounded on'the base of the device by a screw 42 and the other end 43 thereof is connected to the conductor 44 that is carried by an armored cable that serves to connect the rheostat with the indicating instrument. A second conductor 53 connects the contact arm 37 with the indicator 4. The cover 28 has a suitable lug 45 formed on the underside thereof that compresses the meta] armored cable into a socket formed in the base to thereby rigidly secure the cable in.

on the collar 3. Assembly bolts serve to rigidly connect the base, collar and cover plate. The cap 29 is readily removable for the purpose of placing fuel within the tank.

The operation of my device is substantially as follows:

Movement of the float mechanism in respect to changes in the level of fuel in the tank 2 causes the arm 30 to swing about the aXis of the shaft 15, thereby moving contact finger 31 across the contacting face of the resistance winding 14. The change in the relative resistance of various parts of the control circuits with which the rheostat is used causes instrument deflections that indicate the level of liquid in the tank at all times.

The particular forms of apparatus shown and described, and the particular procedure set forth, are presented for purposes of, explanation and illustration. fications of this described apparatus can be made without departing from my invention as defined in the appended'claims.

What I claim is:

1. A float operated mechanism comprising a body having a rheostat receiving chamber, an operating shaft controlled by a float mechanism extending into said chamber, a contact finger carried by said operating shaft within said chamber, a resistance winding concentric with respect to said shaft with which said contact finger engages, a second contact finger of arcuate form within said chamber adapted to yieldingly engage said first finger to electrically connect therewith during the entire range of movement of said first contact finger, and conductor terminals connected to said arcuate finger and to said winding.

2. A float operated mechanism comprising a supplemental collar adapted to be mounted in the opening of a fuel receiving tank, a supporting base carried by said'collar having a portion extending through the open ing in said collar and having a fuel receiving opening overlying the fuel-receiving opening of said tank, a floatoperated shaft carried by the depending portion of the base, a rheostatreceiving chamber offset from said fuel-receiving opening adapted to receive a helical resistance winding of partial cylindrical form, a groove in said rheostat receiving chamber adapted to hold said resistance winding in place, insulating material covering the upper and lower edges of said winding, a compartment adjoining said rheostat.

adapted to receive a contact block, carrying terminal screws, a contact finger carried by said operating shaft, and electrical means connecting the contact finger with one of the terminal screws.

8. A float operated mechanism comprising a body adapted to be mounted in an opening of a fuel receiving tank, said body having a rheostat chamber with an arcuate wall, a float operated shaft concentric with said wall, a resistance winding of a rcuate form fitting against said wall, a contact arm comprising a block of insulating material fixed to said shaft within the chamber and a metal contact finger carried by said block and engaging with said winding, a fixed contact finger of arcuate form in said chamber and positioned between said winding and shaft, said arcuate finger engaging said first mentioned finger throughout its range of movement, and conductors connected to said winding and said stationary contact finger.

4. A float operated mechanism comprising a. body adapted to be mounted in an opening of a fuel receiving tank, said body having a rheostat chamber with an arcuate wall, a float operated shaft concentric with said wall, a resistance winding of arcuate form fitting against said wall, a terminal block of insulating material mounted in said chamber adjacent one end of said winding, an arcuate contact finger fixed to said block and lying between said winding and said shaft, a contact finger carried by said shaft and insulated therefrom, the latter finger engaging said winding and said arcuate finger throughout its range of movement, and conductor terminals carried by said block and connected one to said arcuate finger and one to said winding.

5. The combination with a fuel tank having an internally threaded opening, an externally threaded collar adapted to be screwed into said opening, said collar hav ing an outwardly projecting flange atits upper end, a member detachably fixed to said flange and having an opening in alinement with the opening of the collar and a closure member for sealing the opening, said member having also a chamber at one side of said opening above said flange and a portion depending through the collar into the tank, a rheostat in said chamber, a laterally extending float arm pivoted to the lower end of said depending portion, and means operatively connecting said float arm and rheostat.

In testimony whereof I aifix my signature.

WILLIAM C. MCCOY. 

